Opinion
The multiple personalities of Watson and Crick strands
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* Corresponding author: Reed A Cartwright racartwright@uh.edu
Biology Direct 2011, 6:7 doi:10.1186/1745-6150-6-7
Article mis-states the yeast convention
Ken Wolfe
(2011-03-01 12:28) Trinity College Dublin 
The article mis-states the yeast convention. The Watson strand is the strand with
its 5' end at the left telomere, but the left arm is not always the shorter arm of
a yeast chromosome. In fact, the L arm is longer than the R arm for 7 of the 16 yeast
chromosomes (up to 4 times longer, in the cases of chromosomes IX and XIV).
The left/right nomenclature for yeast chromosome arms dates back to the early days
of yeast genetic maps, but I do not know who introduced it. Cytogenetics is not really
possible for Saccharomyces because the chromosomes are too small and do not have extensive
heterochromatin at centromeres, so nobody knew which arm was the shorter one until
chromosome-sized genetic (and eventually genomic) maps became available. Oliver et
al (Nature 357:38, 1992) then used the well established genetic conventions (chromosome
numbering and L/R arm nomenclature) when they published the first yeast chromosome
sequence. They chose the name Watson for the strand that has its 5' end at the left
telomere.
Competing interests
None.
Yeast Standards
Reed Cartwright (2011-03-08 10:02) University of Houston
After rereading the paper in light of Dr. Wolfe's comments, I can tell that we went a bit too far with the yeast nomenclature. The actual point is that at sometime in the past, what were seen as being short and long arms were standardized as left and right arms (Hong, personal communication). As maps improved, they didn't redo the left and right designations to reflect new sizes. Even if this is also wrong, the spirit of the standardization should still be embraced.
Competing interests
Author of paper.
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